Torque tube vacuum switch

ABSTRACT

A vacuum switch employing a torque tube extending into the evacuated enclosure. A control rod extends within the open external torque tube end and engages the internal end so that an externally applied torque on the rod torsionally deflects the internal end of the torque tube. Rotatable switch elements within the enclosure are activated by this motion. Bridging (double-gap) embodiments and various switching format versions are shown.

te staieS Patent [1 1 Miles June 12, 1973 TORQUE TUBE VACUUM SWITCH FOREIGN PATENTS OR APPLICATIONS lnventgr; D. Miles, saratoga 516,652 1/1931 Germany 200/144 B [73] Assignee: International Telephone and Primary Examiner Robert Macon gelYegraph Corporahon New York Attorney-C. Cornell Remsen; Jr., Walter Jj Baum,

Paul W. Hemminger and Charles L. Johns0n,Jr. [22] Filed: Oct. 12, 1971 21 Appl. No.: 188,385 [571 ABSTRACT A vacuum switch employing a torque tube extending into the evacuated enclosure. A control rod extends 2% 5 200/144 200/83 within the Open external torque tube end and engages "566 B 83 B the internal end so that an externally applied torque on 0 care the rod torsionally deflects the internal end of the 56 R f C1 d torque tube. Rotatable switch elements within the en- 1 e erences l e closure are activated by this motion. Bridging (double- UNITED STATES PATENTS gap) embodiments and various switching format ver- 3,480,750 11/1969 Voshall 200/144 B sions are shown. 2,993,971 7/1961 Pflanz 200/144 B 13 Claims, 8 Drawing Figures PAIENIEU 3. 739. l 21 SKU 2 l 2 1 TORQUE TUBE VACUUM SWITCH BACKGROUND OF THE INVENTION l. Field of The Invention The invention relates to evacuated and hermetically sealed switches.

2. Description of The Prior Art In the prior art, the advantages of encapsulating certain electrical devices such as switches and variable capacitors are well known and widely understood. Among the advantages resulting from vacuum encapsulation of such devices are the ability to withstand much higher voltages over smaller gaps than is otherwise possible in air or other gasses, and the ideal isolation of a vacuum enclosed device in respect to environmental factors such as dust, moisture, etc.

The vacuum enclosures for such devices usually include partially insulating and partially metallic enclosure members. The insulating body members have been variously formed of glass and ceramic materials, both of these insulators being adapted to vacuum sealing between themselves and cooperating metallic enclosure members.

Since the invention herein disclosed concerns vacuum switches, it should be noted that the transfer of mechanical motion from the outside to the inside of an evacuated enclosure is necessary. In the prior art, various types of thrusting and tilting mechanical arrangements have been devised for the actuation of the switching element within the evacuated enclosure. Such motion transfer inherently requires the inclusion of a sealed, yet mechanically flexible portion of the enclosure.

In U.S. Pat. No. 3,406,268 a flexible diaphragm through which a control shaft enters the vacuum enclosure, permits a small amount of tilting action. An example of the more common construction, at least in respect to vacuum switches with moderate or high power handling capability, is that of U. S. Pat. No. 3,555,222. In that prior art reference, the well-known axially extendable metal bellows is used. In accordance with this structure, one or more pairs of axially aligned switch contacts may be brought in or out of contact in response to an externally applied axial translational force.

Although some relatively simple vacuum enclosure structures are known in the prior art, those switches adapted for moderate or high power applications have usually employed this axially extendable bellows to provide the required extendable portion of the enclosure, however.

It is also known to use a through-wall magnetic linkage for effecting switch operation within a sealed envelope. The general concept and form of throughwall magnetic linkages is relatively inefficient in terms.

of the power and structure necessary to bring about reliable operation, and furthermore is generally limited to devices of small physical size.

The aforementioned axially extendable metal bellows so frequently used in vacuum switch assemblies is relatively expensive and, in addition, introduces a differential pressure problem into the device, as a whole. That is to say, external atmospheric pressure tends to bias the bellows into its extended position and the amount of this ambient pressure biasing is related to the external pressure. Thus, in a device that is, for example, to be used in an aircraft, this pressure bias would be only a small fraction of that experienced at sea-level when the aircraft was flying at high altitude. Actuating system designs must account for such differences and if a bellows operated switch is to be held in the position against this external pressure bias, either a latching device or continuous energization of a solenoid actuator is required.

Flexible wall portions or diaphragms, as aforementioned, in small size low power vacuum switches, although less expensive than the usual axial bellows arrangement, can allow only a very small excursion in a unit of reasonably long life. The ambient pressure problem can be a factor, even in the so-called tilt arm mechanism of a device in accordance with U.S. Pat. No. 3,406,268, aforementioned.

SUMMARY In consideration of the foregoing state of this art, and the disadvantages thereof, it may be said to have been the principal object of the present invention to produce a relatively inexpensive vacuum switch adapted to various contact configurations, which would be substantially independent of the external air pressure biasing problem, and which would retain substantially all the advantages of prior art vacuum and gas-filled hermetically sealed switching elements.

A torque tube is employed and is caused to deflect torsionally at its internal end in response to an applied external torque on a control rod, thereby actuating switch elements.

Since the device of the present invention does not have to accommodate axial control motion and does not require the additional housing space taken by the bellows, the present device is inherently capable of greater operating excursion for a given envelope size. The device is, moreover, readily adaptable to a variety of contact configurations, ranging from a bridging type single pole single throw through double pole single throw single pole double throw, reversing, in multiple gap arrangements. The manner in which the advantageous results are achieved will be understood as this specification proceeds.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an axial section of a single-pole single-throw bridging type switch constructed in accordance with the invention.

FIG. 2a is a horizontally-taken section through A-A of FIG. 1.

FIG. 2b is a horizontally-taken BB section of a double pole single throw version of the device of FIG. 1.

FIG. 20 is a single-pole double-throw version, also taken through section BB of a variation of FIG. 1.

FIG. 2d is a reversing switch version of the general device of FIG. 1 as viewed in a BB section.

FIG. 2e is a parallel armature version of FIG. 1 providing two gaps per unit of rotation, as viewed in the BB section.

FIG. 2f depicts a variation of the device of FIG. 2e providing four gaps per unit of rotation.

FIG. 3 depicts a folded torque tube useable as a modification of the torque tube of the FIG. 1 embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, a typical simple embodiment of the present invention will be'described. In FIG.

1, a more or less cylindrical ceramic insulating housing or hollow insulating body 4 has an attached pair of metallic end bells, 2 and 7, vacuum-sealed to it. These seals, typically and 11, are accomplished by a furnace brazing operation after suitable preparation of the ceramic surface according to a process well-known in this art. Similarly, a pair of conductor terminals or posts, 1 and 1', are available for external circuit connections and also extend within the evacuated enclosure through feed-through insulators 12 and 12. These feed-through insulators may well be constructed of the same ceramic material as the body 4, and braze scaling is accomplished typically at 13 and 14 during processing and assembly. The posts 1 and 1 may be separately fabricated into the feed-through insulators 12 and 12, in which case the vacuum seal at 13 would have been pre-formed.

The torque tube 6 is furnace brazed or welded to the end bell 7 at 8, so that the interior of the said torque tube is open to the atmosphere at the bottom of FIG. 1. Torque tube 6 may be formed of a metal providing the required resilience and other characteristics for metals in contact with the evacuated interior of the device. Various copper alloys are considered suitable for this purpose, among them the bronzes of high-strength and spring resilience.

Inside the torque tube 6, a control rod 9 is inserted. A nail-head portion 9 is brazed into place at the innermost end of the torque tube 6, as shown. The brazing of the portion 9 into the torque tube 6 not only provides a secure mechanical bond, but also can be relied upon to provide a vacuum tight end closure of the torque tube. A closed-end ceramic (typically) tube 5 provides an insulator, not only to which the bridging element (shorting bar) 3 may be brazed at 15, but also affording a skirt or sleeve covering substantially the entire length of the torque tube. In this way, flashover protection, as well as direct insulation between the said switch bridging element 3 and all the metal parts conductively associated with the end bell 7,are provided.

It will be noted from close inspection of FIG. 1 that a small clearance exists between the torque tube 6 and the ceramic insulator tube 5. In this way, ceramic tube 5 is not subjected to any of the torsion stress and resulting strain in the torque tube during operation.

FIG. 2a provides additional clarity by showing a planview section AA, so that the relationship of the switch bridging element (shorting bar) 3, the conductive posts 1 and 1 with feed-through insulators and the insulating tube 5, are shown more clearly.

Referring now to FIG. 2b, a double-pole single-throw switch is depicted. The pairs of external contacts are obviously l6 and 19 for one of the poles and 17 and 18 for the other. The bridging elements 20 and 21 are shown closing the circuits between these element pairs. During operation, clockwise rotation of the insulating tube end 5, to which 20 and 21 are securely brazed, interrupts both poles of this switch arrangement with double gaps in each case. 7

Referring now to FIG. 20 a single-pole double-throw configuration involving a three-way switch arm arrangement comprising 24, 25 and 26, is seen. In this configuration, a common pole, either 21 or 22, is connected through 25 to 23 in one position of the switch (illustrated), and after counter-clockwise rotation of 5, would be connected to 20 through 24.

In FIG. 2d, a slightly more complex arrangement involves the use of additional terminals sealably projecting through the ceramic insulating tube 4 or with additional insulation through the end bell 2 and provides external connections via 27 and 28. The connections 29 and 32 need not be external in this instance, the additional external connections being provided by 33 and 31.

As illustrated, the connection 27 provides circuit continuity through a springfinger 37 resting in a slot in 27, as shown, via 35, 29, and 33 and thence out at 31. Similarly, a connection from 28 via slot 33, springfinger 36 and 32, 34 and thence out to 30, is extant in this switch position. With clockwise rotation of 5, it will be seen that terminal 27 becomes connected to 30 and 28 to 31, thereby providing a reversing double-pole switch action.

It is also possible to provide multiple gapping, as illustrated in FIGS. 2e and f. In FIG. 2e, external connections at 40 and 41 are in continuity via 43, 39, 45, 41, 44, 42 and 46, essentially, affording two double-gap parallel paths in a single pole switch. Clockwise rotation of 5 will be seen to break both of these parallel paths in double-gap fashion.

In FIG. 2f, continuity in a single-pole four-gap switch unit exists between 48 and 50, as shown, via 48, 53, 49, 51, 47, 52, and 50. With clockwise rotation, gaps appear between 47 and 52 and also between 50 and 52, as well as between 53 and 48 and 53 and 49. In this particular configuration, the resulting single-pole arrangement comprising four vacuum gaps in series could be expected to provide a relatively high voltage capability.

Referring now to FIG. 3, a folded torque tube configuration which effectively adds the deflection of three separate concentric torque tubes per unit of applied force couple is shown. In this configuration of the torque tube, operation is as if the tube itself were three times longer than that of FIG. 1. A similar torque control rod 9 is provided but without the nailhead 9, as in FIG. 1. Instead, the internal end of the rod 9 would be securely brazed to a closure plate at 56, which is part of the outside or largest diameter tube L-3. The next smallest diameter tube, L-2, is connected to L-3 via a weld bead around a common circumference at 55. Similarly, the smallest diameter, or inside tube L-l, is connected to the L-2 tube by a weld 54. The tube closure plate 56 would be in contact with the switch bridging element 3 via a similar ceramic insulating tube, such as 5 of FIG. 1 brazed much as at 15 in FIG. 1.

It will be seen from this description that the switch of the present invention readily lends itself to a variety of contact and torque tube arrangements. Due to its compact and rigid structure, it is inherently less sensitive to shock and vibration than most prior art configurations.

It will be realized by those skilled in this art that the torque tube, either in the form shown in FIG. 1 or that of FIG. 3, may be preloaded such that any of the'various embodiments shown in FIG. 2 can be converted from normally closed to normally open versions. That is to say, for example, in FIG. 2b if a torque tube were pre-loaded with a counterclockwise torque when the contacts were as shown, the release (or counteraction by twisting the rod 9) of this would cause the switch contacts to stand open. I

Numerous modifications and variations within the scope of this invention will suggest themselves to those skilled in this art. Accordingly, it is not intended that the scope of the invention should be limited by the drawings and the description herewith, these being typical and illustrative only.

What is claimed is:

l. A vacuum switch comprising:

a hermetically sealed enclosure;

a hollow torque tube projecting into said enclosure, said tube being sealed at one open end to an opening in said enclosure and closed at the internal end of said tube projected into said enclosure;

means for applying a force couple, effective at said internal end of said torque tube in response to an applied external torque for producing elastic torsional displacement of the internal end of said tube about its cylindrical axis;

at least one stationary switch contact element within said enclosure;

at least one movable switch contact element within said enclosure;

and a mechanical linkage connected to said torque tube within said enclosure for making and breaking contact between said stationary and movable contact elements, thereby to effect switch operation in response to said externally applied torque.

2. Apparatus according to claim 1 in which said enclosure is evacuated and said torque tube is made of a relatively elastic metal.

3. Apparatus according to claim 1 in which said stationary switch contact element includes a conductive extension through the wall of said enclosure for external connection.

4. Apparatus according to claim 3 in which there are at least two of each of said stationary and movable con- 5 tact elements and said mechanical linkage comprises at least one arm extending bilaterally from the internal end of said torque tube within said enclosure said arm further supporting and electrically interconnecting one of said movable contact elements substantially at each end of said arm, thereby to produce a bridging switch structure having a double vacuum gap during its open condition.

5. Apparatus according to claim 4 including insulating means for electrically isolating said moving contacts from said torque tube.

6. Apparatus according to claim 1 in which said means for applying a force couple effective at said internal end of said torque tube for producing elastic torsional displacement of the internal end of said tube comprises a rod member mechanically secured to the said closed internal end of said tube and projected through the center of said tube to a point external of said end of said tube sealed to said enclosure.

7. Apparatus according to claim 1 in which said torque tube comprises an odd number of three or more concentric tubes fitting together with at least slip-fit clearance therebetween, the smallest diameter tube being sealed at one open end to an opening in said enclosure and the largest diameter tube being closed at its internal end projecting within said enclosure, said means for applying a force couple comprises a rod member affixed to said closed end of said largest diameter tube and extends through the center of said smallest tube to an external point, and said remaining tubes are joined at their open edges in a manner to form a folded torque tube.

8. Apparatus according to claim 7 in which the individual tubes of said folded torque tube and joined at edges in juxtaposition, the smallest and next smallest being joined at their edges toward the interior of said enclosure, the next smallest and the third smallest being joined at opposite edges in juxtaposition, the third smallest and the fourth smallest being joined at their edges toward the interior of said enclosure and thereafter in that alternation throughout the remainder of said tubes comprising said folded torque tube.

9. Apparatus according to claim 2 in which said evacuated enclosure comprises a hollow, generally cylindrical body member of insulating material and a pair of metallic end bells sealed thereto, at least one pair of said stationary contacts are provided by at least one corresponding pair of conductive posts extending externally and internally through corresponding sealed feed-through insulators in a first of said end bells, said torque tube is sealed at said one open end through an opening in the second of said end bells, said mechanical linkage includes at least one conductive armature element arranged to act as a shorting bar between a corresponding pair of said conductive posts in one condition of said externally applied torque and to provide a double vacuum gap in another condition of said externally applied torque, and insulating means are included between said torque tube and said armature element.

10. Apparatus according to claim 9 in which said insulating for said armature element comprises a closed end ceramic tube enclosing and sealed to said torque tube over its surface within said enclosure.

11. A device for producing torsional mechanical motion within a hermetically sealed vessel, comprising:

a tubular member projecting within the interior of and forming a part of the enclosure of said vessel, said tubular member being open at its external end and sealed at its internal end;

and means extending within the interior of said tubular member for applying a torsional force effective at said sealed internal end thereof to produce rotational deflection of said internal end elastically.

12. A vacuum switch comprising:

a hermetically sealed enclosure;

a folded torque tube projecting into said enclosure, said folded torque tube comprising an odd number of three or more concentric hollow tubes fitting together with at least slip-fit clearance therebetween, the smallest diameter tube being sealed around the perimeter of one of its open ends to an opening in said enclosure and the largest diameter tube being closed at its internal end'projecting within said enclosure, said remaining tubes being joined at their open edges in a manner to form said folded torque tube;

rod means for applying a force couple effective at said internal end of said largest diameter tube in response to an applied external torque for producing elastic torsional displacement of said internal end of said largest diameter tube about the cylindrical axis of said folded torque tube, said rod means extending through the center of said smallest diameter tube from an attachment to said closed end of said largest diameter tube to an external point;

at least one stationary switch contact element within said enclosure;

at least one movable switch contact element within said enclosure;

being joined at their edges toward the interior of said enclosure, the next smallest and the third smallest being joined at opposite edges in juxtaposition, the third smallest and the fourthsmallest being joined at their edges toward the interior of said enclosure and thereafter in that alternation throughout the remainder of said tubes comprising said folded torque tube. 

1. A vacuum switch comprising: a hermetically sealed enclosure; a hollow torque tube projecting into said enclosure, said tube being sealed at one open end to an opening in said enclosure and closed at the internal end of said tube projected into said enclosure; means for applying a force couple, effective at said internal end of said torque tube in response to an applied external torque for producing elastic torsional displacement of the internal end of said tube about its cylindrical axis; at least one stationary switch contact element within said enclosure; at least one movable switch contact element within said enclosure; and a mechanical linkage connected to said torque tube within said enclosure for making and breaking contact between said stationary and movable contact elements, thereby to effect switch operation in response to said externally applied torque.
 2. Apparatus according to claim 1 in which said enclosure is evacuated and said torque tube is made of a relatively elastic metal.
 3. Apparatus according to claim 1 in which said stationary switch contact element includes a conductive extension through the wall of said enclosure for external connection.
 4. Apparatus according to claim 3 in which there are at least two of each of said stationary and movable contact elemenTs and said mechanical linkage comprises at least one arm extending bilaterally from the internal end of said torque tube within said enclosure said arm further supporting and electrically interconnecting one of said movable contact elements substantially at each end of said arm, thereby to produce a bridging switch structure having a double vacuum gap during its open condition.
 5. Apparatus according to claim 4 including insulating means for electrically isolating said moving contacts from said torque tube.
 6. Apparatus according to claim 1 in which said means for applying a force couple effective at said internal end of said torque tube for producing elastic torsional displacement of the internal end of said tube comprises a rod member mechanically secured to the said closed internal end of said tube and projected through the center of said tube to a point external of said end of said tube sealed to said enclosure.
 7. Apparatus according to claim 1 in which said torque tube comprises an odd number of three or more concentric tubes fitting together with at least slip-fit clearance therebetween, the smallest diameter tube being sealed at one open end to an opening in said enclosure and the largest diameter tube being closed at its internal end projecting within said enclosure, said means for applying a force couple comprises a rod member affixed to said closed end of said largest diameter tube and extends through the center of said smallest tube to an external point, and said remaining tubes are joined at their open edges in a manner to form a folded torque tube.
 8. Apparatus according to claim 7 in which the individual tubes of said folded torque tube and joined at edges in juxtaposition, the smallest and next smallest being joined at their edges toward the interior of said enclosure, the next smallest and the third smallest being joined at opposite edges in juxtaposition, the third smallest and the fourth smallest being joined at their edges toward the interior of said enclosure and thereafter in that alternation throughout the remainder of said tubes comprising said folded torque tube.
 9. Apparatus according to claim 2 in which said evacuated enclosure comprises a hollow, generally cylindrical body member of insulating material and a pair of metallic end bells sealed thereto, at least one pair of said stationary contacts are provided by at least one corresponding pair of conductive posts extending externally and internally through corresponding sealed feed-through insulators in a first of said end bells, said torque tube is sealed at said one open end through an opening in the second of said end bells, said mechanical linkage includes at least one conductive armature element arranged to act as a shorting bar between a corresponding pair of said conductive posts in one condition of said externally applied torque and to provide a double vacuum gap in another condition of said externally applied torque, and insulating means are included between said torque tube and said armature element.
 10. Apparatus according to claim 9 in which said insulating for said armature element comprises a closed end ceramic tube enclosing and sealed to said torque tube over its surface within said enclosure.
 11. A device for producing torsional mechanical motion within a hermetically sealed vessel, comprising: a tubular member projecting within the interior of and forming a part of the enclosure of said vessel, said tubular member being open at its external end and sealed at its internal end; and means extending within the interior of said tubular member for applying a torsional force effective at said sealed internal end thereof to produce rotational deflection of said internal end elastically.
 12. A vacuum switch comprising: a hermetically sealed enclosure; a folded torque tube projecting into said enclosure, said folded torque tube comprising an odd number of three or more concentric hollow tubes fitting together with at least slip-fit clearance therebetweeN, the smallest diameter tube being sealed around the perimeter of one of its open ends to an opening in said enclosure and the largest diameter tube being closed at its internal end projecting within said enclosure, said remaining tubes being joined at their open edges in a manner to form said folded torque tube; rod means for applying a force couple effective at said internal end of said largest diameter tube in response to an applied external torque for producing elastic torsional displacement of said internal end of said largest diameter tube about the cylindrical axis of said folded torque tube, said rod means extending through the center of said smallest diameter tube from an attachment to said closed end of said largest diameter tube to an external point; at least one stationary switch contact element within said enclosure; at least one movable switch contact element within said enclosure; and a mechanical linkage connected to said torque tube within said enclosure for making and breaking contact between said stationary and movable contact elements to effect switch operation in response to said externally applied torque.
 13. Apparatus according to claim 12 in which the individual tubes of said folded torque tube and joined at edges in juxtaposition, the smallest and next smallest being joined at their edges toward the interior of said enclosure, the next smallest and the third smallest being joined at opposite edges in juxtaposition, the third smallest and the fourth smallest being joined at their edges toward the interior of said enclosure and thereafter in that alternation throughout the remainder of said tubes comprising said folded torque tube. 